The present invention relates to the arrangement of the bottom bracket and the bottom bracket bearing axle of a bicycle, which uses two socket-like axle bearings to support the revolution of the bottom bracket bearing axle.
The chain drive of a bicycle is generally comprised of a bottom bracket bearing axle mounted in the bottom bracket, two pedals respectively coupled to two opposite ends of the bottom bracket bearing axle by a respective crank, a chain wheel fixedly mounted around the bottom bracket bearing axle and coupled to the rear sprocket by a chain. FIGS. 1 and 2 show the arrangement of the bottom bracket bearing axle in the bottom bracket according to the prior art. This arrangement comprises two externally threaded end caps respectively threaded into two inner threads in the bottom bracket at two opposite sides, a bushing and a ball bearing respectively mounted inside the bottom bracket around the bottom bracket bearing axle to support the revolution of the bottom bracket bearing axle. This arrangement has drawbacks. When in use, the ball bearing tends to be forced to displace. Another drawback of this arrangement is its shot service lift. Because the contact between the bottom bracket bearing axle and the balls of the ball bearing are limited to spots, less bearing surface is provided to support the revolution of the bottom bracket bearing axle. Furthermore, the ball bearing must the lubricated with a lubricating grease before its installation.
The present invention has been accomplished to provide a bicycle bottom bracket and bearing axle arrangement which eliminates the aforesaid drawbacks. According to the present invention, two nuts and two clamps respectively fastened to the bottom bracket bearing axle to hold two socket-like axle bearings at two opposite ends of the bushing around the bottom bracket bearing axle, and a cushion mounted around the bottom bracket bearing axle between one nut and one clamp and having inward teeth respectively engaging in respective longitudinal sliding grooves the bottom bracket bearing axle. The socket-like axle bearings are respectively made from oil modified resin, therefore no lubrication is needed. Because the inside wall of each socket-like axle bearing is disposed in contact with the periphery of the bottom bracket axle bearing, the broad contact area between the socket-like axle bearings and the bottom bracket bearing axle smoothly supports the revolution of the bottom bracket bearing axle.